Sharif Digital Repository

The IEC61850 Standard was introduced for IED, Intelligent Electronic Device, in a power substation so that different devices from different manufacturers could work together. Each of these devices must be configured to start communication. Chapter 6 of the IEC61850 Standard discusses the configuration language of these devices, SCL, Substation Configuration Language, as well as how to write it in detail.A failure or denial-of-service attack can occur in a power substation if a tampering or embedding a breach in devices’ configuration occurs. To discover such attack, one can model the behavior of all the components in the SCL language using a language describing the behavior, and then compare... 

Planning safe rendezvous and docking trajectories between two spacecrafts has a high importance in the space applications. In order to make two spacecrafts moving in different orbits closer, two stages must be completed simultaneously: First the implementation of rendezvous maneuver which deals with the generation of control/guidance commands leading to trajectories that lead the chaser towards the target. Second the docking maneuver incorporation which makes the two spacecrafts closer with the relative zero attitude. Various approaches have been dealt with till now using the analytical and numerical approaches generally considering rendezvous, not the docking maneuver. These approaches... 

Aiming to improve the extraction performance of wind energy has led to the noticeable increase of the structural dimensions in the modern wind turbines. The larger blade with more flexibility experiences large structural deformation even under nominal operational loading, so the nonlinear modeling and analysis of these structures have become as important subject of the recent wind turbine researches. In this dissertation, the geometrical exact model of the rotating wind turbine blade under the effects of the tower tip's motion, and also the operational loading comprising the aerodynamic and gravitational loadings is presented. In this way, the geometrical exact beam formulation is developed... 

Today, the global environmental restrictions as well as; energy problems have directed researchers toward developing ideas of producing a clean liquid fuel from coal or natural gas as a major research topic. In this regard, a special attention is paid to the dimethyl ether (DME) as a clean material containing 34.8% oxygen possessing enough positive potential to replace the diesel and LPG fuels. One of the most economic routes for producing the DME is known to be the direct conversion of the synthesis gases and carbon dioxide first to the methanol and then its dehydration to the DME. Moreover, the DME is not limited to a particular country or resource area since small reservoirs of natural... 

Sustainable energy is an important and necessary subject. A significant number of studies address the increasing energy production ratio per its cost. To this end, first of all we should increase the energy production. Second, damage and costs of production, set up and maintenance must be reduced. Control is one of the most important and effective tools in the way of achieving these purposes. The problem of controlling a wind turbine is generally divided into two sections of controlling the power chain and yaw control. In this research, both subjects have been investigated.Since there are some problems in measuring the wind speed, controlling the power chain requires prediction of the wind... 

The synthetic aperture radar (SAR) is a microwave imaging radar that achieves high resolution while taking advantage of pulse compression technology and the Doppler effect. In typical radar systems, in order to obtain a good azimuth resolution, one should use an antenna with big aperture. However this is not possible in many cases. SAR has overcome this problem by moving the antenna and so making a synthetic aperture. In inverse SAR (ISAR) the radar antenna is static and synthetic aperture is created by the movement of target. Typical SAR imaging aims at the static targets and when the target is moving, it does not operate well. When detecting moving targets by SAR, both radar and target are... 

This thesis presents several methods time-frequency based approach for classifying the vibration signals of rotatery machine. It uses the features extracted from the time-frequency distribution (TFD) of the vibration signal segments. Results of applying the method to a database of real signals reveal that, for the given classification task, the selected features consistently exhibit a high degree of discrimination between the vibration signals collected from healthy and fault machine. A comparison between the performances of the features extracted from several TFDs shows that the STFT slightly outperforms other reduced interference TFDs.


 

A group of vehicles are contributed to follow static or dynamic targets in a cooperative target tracking problem. The vehicles estimate the future location of dynamic targets based on the information they receive from other vehicles and targets. Noting to these estimations, the vehicles are able to decide the best movement toward the targets. Various control methods have been presented to solve different problems of target tracking which the majority of them proposed optimal control solutions. A new approach to the problem of tracking dynamic targets via cooperative multi-vehicle systems under the receding horizon control of the vehicles is proposed in this dissertation. A receding horizon... 

In this Thesis, a new algorithm is presented to cooperatively guide a set of robots, modeled as dynamic vehicles, toward a moving object while their heading angles variation are limited and collision avoidance is also required. The trajectory of object has unknown behavior, such that, at each moment in time, during the mission period, the available information about the object's trajectory is merely its position and instantaneous velocity. Due to this situation, vehicles are supposed to determine their movements, based on the predicted object's trajectory. To meet the goals of the algorithm, a time-decreasing reward is associated with the object, such that vehicles can collect the reward... 

Nowadays, economical extraction of oil and gas, and their products is an important issue for many countries. Up to now, vertical wells have been used for oil extraction but some wells exist that they cannot be reached by using vertical drilling; for example the wells under a sea. Therefore, this makes the governments and scientists determined to find a new way to reach them. Horizontal drilling is one of the new ways to reach such worthy wells. In this project, dynamics of the horizontal drill string is studied. Then, according to the forces that affect the dynamics of drilling, its vibration is analyzed. After finding the boundary conditions and normal modes of the system with using mode... 

Prescribing and consuming drugs more than necessary is considered polypharmacy, which is both wasteful and harmful. In this study, an innovative data mining framework is developed for analyzing prescriptions regarding polypharmacy. The approach consists of three main steps: pre-modeling, modeling, and post-modeling. In the first step, after collecting and cleaning the raw data, several novel features are extracted for physicians and patients. In the modeling step, decision trees are applied to generate a set of If-Then rules to detect and describe physicians’ features or patients’ features associated with polypharmacy. A novel approach based on the response surface methodology (RSM) is... 

Thyroid gland is one of the important internal organs of the body that is responsible for T3 and T4 hormones secretion. Concentration of these hormones directly influences growth of body, thus measurement concentration of thyroid hormones is one of the most common experiments all of the world, specially in our country that Hypothyroidism is common among people. Secretion of hormones in thyroid gland controlled by TSH (thyroid Stimulating Hormone) that released from Pituitary gland. TSH concentration is opposite of level of thyroid secretion. Because of interconnected relationship between these three hormones, measurement of each of them is so important. Many researches for developing... 

In this Thesis, the necessary steps to implement near-optimal atmospheric flights in order to create micro and partial gravity condition has specified. This documentary has been prepared in a comprehensive way. The goal of this project is to reach the optimal throttle and elevator inputs and consequently optimal paths to perform the maneuver with maximum time. The basis of my work is to integrate two methods of tabu search and continuous ant colony system in order to find the best match for inputs. As a result, the aircraft’s proper inputs as a function of time can be accommodated. The constraints here refers to the safety of the flight, which are maximum operating speed, stall angle of... 

The visibility is one of the most important problems in computational geometry. Two points are said to be visible to each other, if the line segment that joins them does not intersect any obstacles. The art gallery problem is a well-studied visibility problem in computational geometry. It originates from a real-world problem of guarding an art gallery with the minimum number of guards who together can observe the whole gallery. In many of applications, the “guards” are “landmarks” deployed in an environment to help provide navigation and localization service to mobile robots. The mobile device communicates with these landmarks through wireless, or other “line-of-sight” signaling... 

Air conditioning systems are one of the main parts of buildings, and their performance is very important, especially during the peak heat and cold days, both in terms of providing comfort area for the people and in terms of energy consumption. These systems control the temperature and humidity inside one or more target zones using heating, cooling, humidification, and dehumidification processes. One of the most common solutions to optimize the performance of air conditioning systems is the use of control systems. In this study, a nonlinear multi input-multi output dynamic model of a two-zone variable air volume & temperature air handling unit is considered for operation in the summer season.... 

Heat sources with temperatures less than 100 °C are available in various processes in the form of waste heat and from renewable sources such as solar energy. One of the methods of gaining benefit from these ubiquitous and abundant heat sources is using thermal harvesters that convert low-temperature heat into electrical energy without the need for the power grid. Portable harvesters can be a reliable and low-cost option for providing stable energy for low-power electronic devices such as wireless sensors. Many studies have been conducted at the global level to design and develop efficient low-temperature heat harvesting mechanisms. However, each of them is associated with fundamental... 

Nowadays, machine learning is used to solve various problems, and different machine learning models have increasingly become a part of our daily lives. This raises the importance of a more detailed examination of the models' outputs. In sensitive areas such as medical uses, this issue becomes even more critical, and using these models without having a framework to quantify the uncertainty of the outputs can lead to significant challenges and hinder their broader application. Conformal prediction is one of the frameworks that can help quantify the uncertainty of outputs. This framework is model-agnostic, meaning that we can use it for any model, including black-box models. The outputs of this... 

Renewable energies and their various types have been recognized as sustainable solutions to address the challenges arising from increasing energy consumption and environmental issues. The use of wind energy as one of the renewable energy sources has particular advantages, considering it as one of the most sustainable energy sources. One of the key factors in wind turbine development is the diversity and multiplicity in their structural designs. Therefore, the design of wind turbine structures with characteristics such as suitable strength, high energy efficiency, optimal cost, and high reliability is of great importance. By employing various sciences such as vibrations and optimization in... 

Patients with a single ventricle disease who have undergone Fontan surgery have always had long-term complications. These complications include pulmonary artery stiffness and decreased ability to exercise. In fact, due to removal of the right ventricle from the circulatory system, blood pressure and pulsatility inflow to total cavopulmonary connection (TCPC) are reduced following this surgery. Creating waves (radial displacement) on the IVC (Inferior Vena Cava) wall can increase pulmonary flow pulsations. The Objective of this study is to test the effect of induced wave amplitude on the pulmonary flow pulsations at the rest condition. Computational fluid dynamic (CFD) simulations were... 

Pipe freezing has become well established in industry as a method of short-termisolation in order to carry out maintenance or repairs. It is often necessary to repair system components without plant shutdown or drainage of system having many piping structures which may have hazardous or expensive fluid. Therefore, a series of tests has been arranged to investigate the ice plug formation in two standard pipes with different diameter size. The freeze zone on the pipe has been created by means of an aluminum jacket which liquid nitrogen flows in it. In the tests the freezing time, amount of liquid nitrogen usage andthe pressure tolerance of ice plug have been determined. Moreover, the numerical...